Its rather frightening, downbeat title aside, this is a decidedly uplifting story. The day before his family leaves to visit Grandma and Grandpa in Iowa, nine-year-old Mikey packs his clothes, taking special care to leave his bathing suit behind. Terrified of swimming, he is determined to avoid the water. But he has no such luck. His parents have signed him up for lessons, and it seems that swimming is on the agenda at every turn (``Does everyone in the world have to have a pool or a watering hole or some other stupid place to drown?''). Punctuating her book with much lighthearted banter and realistic sibling bickering, Napoli ( The Magic Circle ) deftly delivers a worthwhile message to youngsters having trouble overcoming a fear and making a leap--into the water or elsewhere. Heeding the advice of his mother and grandmother, Mikey learns to think positively and act confidently (and to swim). Napoli's snappy dialogue and compact sentences--and Poydar's animated drawings--make this a good selection for reluctant readers. Ages 7-10. (Mar.)